1. Technical Field
The present invention relates to a dual-bus riser card for an expansion slot, and more particularly relates to an improved dual-bus riser card for an expansion slot in a computer system for operatively supporting expansion cards of at least two different types of bus architectures in which the expansion cards are mounted horizontally in a computer chassis to minimize the height requirement of the computer chassis.
2. Background Art
As personal computers advance to satisfy the need for increased memory capacity, faster program computation, higher display resolution and faster presentation of information to the computer user, the greater flexibility, adaptability and upgradibility of the personal computers to new and improved technologies are required to accept any of the readily available industry standard expansion boards with different types of bus architecture such as the Industry Standard Architecture (ISA) bus, the Extended Industry Standard Architecture (EISA) bus and PCI bus.
Traditionally, expansion boards are mounted vertically on corresponding connectors or expansion slots on a motherboard of the computer system for upgrading purposes. Since the expansion boards are mounted vertically from the motherboard of the computer system, the computer chassis becomes unnecessarily large. In order to minimize the size and height of the computer chassis, riser card is used as an expansion board assembly to accommodate a single or a plurality of expansion boards mounted horizontally on corresponding bus slots formed therein when its edge connector is mounted vertically on a motherboard expansion slot of the computer system.
Conventional riser card for an expansion slot in a computer system for supporting an expansion board such as disclosed in U.S. Pat. No. 5,174,762 for Circuit Board Adapter For Computer System issued to Hoppal et al., or for supporting a plurality of expansion boards such as disclosed in U.S. Pat. No. 5,406,453 for Computer Chassis Planar/Riser Card Assembly issued to Cusato et al., however, accommodates expansion board of only one type of bus architecture, that is, either an ISA bus or an EISA bus. Some other riser card configurations such as disclosed in U.S. Pat. No. 5,519,573 for I/O Riser Card For Motherboard In A Personal Computer/Server issued to Cobb et al., are mounted on a motherboard socket serving as an input/output device for connecting a video monitor, mouse, printer to the computer system. Since the conventional riser card for an expansion slot in the computer system such as those disclosed particularly in Hoppal et al. '762 and Cusato et al. '453 is fixed to a single type of bus architecture and is mounted only in one direction on a motherboard of the computer system, they are neither readily available for advanced computer system utilizing any combination of ISA, EISA or PCI bus or future bus expansions, nor are they useful and effective in simplifying the motherboard.
One recent improvement in the riser card configuration is disclosed in U.S. Pat. No. 5,513,329 for Modular Host Local Expansion Upgrade issued to Pecone. In Pecone '329 a riser card is adapted to accommodate expansion boards of different combinations of ISA, EISA or local bus architectures in corresponding bus slots formed therein. While the riser card configuration of Pecone '329 has merits in its own right, it is my observation that since all the expansion boards are mounted uniformly on one side of the riser card, the formation of the bus slots in the riser card for different ISA or EISA board during manufacture can be ineffective, time consuming and consequently costly. Moreover, the riser card configuration as disclosed by Pecone '329 does not effectively utilize the spatial arrangement of a motherboard of the computer system.